Plastic pallets are in common use in many industries. They are used as load platforms for easily transporting loads using material handling equipment, such as fork lift trucks and the like. A typical pallet has a deck with an upper surface for supporting a load and a lower surface which is engaged by the material handling equipment when in transit.
The load on a typical pallet causes the pallet deck to deflect concave upward in the areas between the feet and to compress the feet of the pallet, while lifting or transporting the pallet by engaging the material handling equipment causes the pallet deck to deflect concave downward. Constant movement of the pallet subjects a pallet deck to a continuous cycle of upward and downward deflections, weakening the pallet structure and eventually causing the pallet to fail.
One method which prolongs the life of a plastic pallet is to add material to the structural components of the pallet increasing the pallet stiffness and capability to withstand many deflection cycles. This method, however, increases the weight and cost of the pallet.
Plastic pallets have in general been made by either rotational molding, single of twin sheet vacuum thermoforming, or injection molding. Rotational molding and vacuum thermoforming can be used to create voids within the pallets, but also results in thin walled sections of relatively low strength. Injection molding is capable of forming thicker walled sections and solid reinforcing ribs resulting in a pallet of solid material with less strength than what the same volume of material is capable of. Thus, a need exists for a method of increasing the strength of material handling pallets, without increasing the weight or cost.